To meet their need for nitrogen in the restricted foraging environment provided by their host plants, some arboreal ants deploy group ambush tactics in order to capture flying and jumping prey that might otherwise escape^{1, 2, 3, 4}. Here we show that the ant Allomerus decemarticulatus uses hair from the host plant's stem, which it cuts and binds together with a purpose-grown fungal mycelium, to build a spongy 'galleried' platform for trapping much larger insects. Ants beneath the platform reach through the holes and immobilize the prey, which is then stretched, transported and carved up by a swarm of nestmates. To our knowledge, the collective creation of a trap as a predatory strategy has not been described before in ants.

1. Laboratoire d'Évolution et Diversité Biologique (UMR CNRS 5174), Université Toulouse III, 31062 Toulouse, France
2. Department of Animal Biology, University of Illinois at Urbana–Champaign, Urbana, Illinois 61801, USA
3. Laboratoire de Psychologie Sociale de la Cognition (ESA CNRS 6024), Université Blaise Pascal, 63037 Clermont-Ferrand, France

Correspondence to: Jérôme Orivel¹ Email: orivel@cict.fr